It is weird. It's also weird that Mac DeMarco is now technically moving in the same circles as WWE superstars. They crossed paths on The Tonight Show with Jimmy Fallon, where both were invited guests; DeMarco to play ‘One More Love Song’ from his latest album, and Cena to plug the second season of his reality show, American Grit. The idea of DeMarco appearing on the world’s longest-running talk show remains almost as patently absurd now as it would have been when the Canadian was a teenager working in road construction in his native Edmonton (his nickname on the crew was ‘Lil Bitch’), or when he made his first forays into music back in 2009, ingratiating himself into Vancouver’s underground scene and playing live shows that outraged public decency as a matter of routine.

Even when his career began to take off, after he signed with hallowed Brooklyn label Captured Tracks in time for 2012’s deeply weird debut EP Rock And Roll Night Club, this was not a man anybody was looking at and thinking: “Matter of time before this guy’s on an A-list chat show”. That same year’s first full-length proper, 2, offered plenty of ramshackle charm as well as indications of a preternatural grasp of melody, but no obvious indication that this was a star in the making. The record that launched DeMarco to that level, Salad Days, was recorded in a tiny bedroom with little more than rudimentary gear, a limitless flow of cigarettes and an attitude to timekeeping that did not allow for perfectionism; he laid down the final drum track with minutes to spare before he left for the airport to begin the album’s tour.

By the time he followed it up in 2015 with a profoundly sad collection of love songs, Another One, he had cemented his status as one of indie rock’s leading lights, but remained entirely grounded, living in a decidedly serviceable house by the water in what you might charitably describe as one of New York City’s less bijou neighbourhoods. Famously, he gave out the address at Another One’s conclusion, along with an invitation to listeners to stop by for coffee. If the dedication of DeMarco’s young fans, many of whom present as mini-me versions of him at his concerts with their staunch adherence to his unrefined dress code, was somehow still lost on him when he made that decision, it wouldn’t have been a few months later: hundreds took him up on his offer.

That is not the sort of humble behaviour you’d readily associate with a musician at this height of success and the fact that he’s managed to maintain it whilst still ticking off the kind of career milestones most only dream of – selling out two nights at Brixton Academy back in May, and headlining both New York City’s Radio City Music Hall and California’s Greek Theater this month – suggests that it never was a persona or a put-on. DeMarco is the genuine article and an absolute character – quite right that he’s on national television and shooting the shit with the walking embodiment of hustle, loyalty, and respect. Who, by the way, is apparently one of the good guys.

“Cena was really cool. A very nice guy,” DeMarco concludes from his Los Angeles home, to which he’s just returned after a European tour. “We did Conan O’Brien a couple of years ago, so I went into this one thinking: ‘No problem, been here before, all gonna be OK.’ And then you get to the green room, and you’re watching the show happen on the screen as it’s being taped, and you remember that there’s this weird weight to bands playing late night TV – The Beatles on Ed Sullivan, or Zevon on Letterman. The nerves start jangling, even as silly as the whole thing is.”

Any admission of jitters from a man who is so laid back as to be almost horizontal is always going to be a bit disarming, but the truth is that with every new release, DeMarco comes across more and more as somebody keenly in touch with his emotions. You don’t even have to scratch especially far beneath the surface of the songs themselves; it’s the onstage goofball with a penchant for copious Jameson consumption and wanton nudity that’s so frequently acted as a smokescreen. For every done-to-death anecdote about him thrusting a drumstick up his arse and delivering an extraordinarily loose reinvention of U2’s ‘Beautiful Day’, there’s a deeply melancholic reflection on the loss of his youth on Salad Days.

For every time he’s reimagined The Phantom Menace and failed to be shackled by the boundaries of good taste (Google his ‘review’ of Star Wars: The Force Awakens), you can find a devastating, desperate ode to heartache on Another One. And for every bit of well-lubricated stage banter replete with toilet humour, there’s a moment of sober rumination on This Old Dog, DeMarco’s third long-player. Once again, he comes across every inch as that kid in school who did nothing but dick around all year and yet still inexplicably managed to ace every exam.

“It was funny that a lot of the reviews for this record were like, ‘Hmm - not goofy enough. Where’d the goofy guy go?’” says DeMarco of an album that touches upon ageing, regret, and even death. “A lot of the press were talking about how it didn’t seem as carefree as in the past, but a lot of Salad Days was me being this grumpy little guy who was sick of doing too much touring, and some of the songs on Another One were bummers – super sad. So I’m not sure where those guys were back then, but I don’t mind being put into their box. I’m still the guy inside the box, and I know what I like. That’s good enough for me.”

The unshakable sense that the years are slipping by too quickly for his liking is one that DeMarco has constantly written about, even as he’s enjoyed the sort of success he could only have imagined five years back; it marks him out as a perennial nostalgist and surfaces throughout This Old Dog, especially on tracks like ‘Dreams From Yesterday’. It’s something that hits hardest when he finally steps away from the road for a prolonged period, which explains how it seeped into these new songs even as he was finally settling into the most stable period of his adult life, swapping Brooklyn for Los Angeles and a taste of domestic bliss.

“I bought a house, and it’s just me and my girlfriend for the first time,” relates DeMarco, who three years ago was living in a cramped, windowless room in a Bushwick warehouse, the dubiously-monikered Meat Wallet. “My life’s changed a lot, and I’m more comfortable than I’ve ever been – we’ve made some money playing shows. I think I’ll always have that feeling of: ‘Oh dear, the great demise’, but I think a big thing now is a kind of battle against apathy, of becoming bored with being in this settled situation.”

He also doesn’t want to drift back into the slightly bratty, resentful frame of mind that he found himself in around the time he was writing Salad Days. “That’s something that’s kind of a reality check now: if I see myself turning into something I don’t necessarily want to be, it’s like: ‘OK! Wake up!’ I know I’m not really old yet – I think it’s just a reaction to getting off tour after a few years and going: ‘Where the fuck did my twenties go?’ It’s not like I’m trying to suck all the marrow out of life.”

To his more dedicated followers, certain figures in DeMarco’s life have become familiar over the years, including his mother, Agnes, who sometimes tours with her son, interacts with his fans daily on Facebook, and has participated in a handful of video interviews with him that are worth looking up for irrefutable proof that he is very much a chip off the old block. It’s his potential similarities to his father, though, that plague his thoughts on This Old Dog, especially on opening track ‘My Old Man’, on which he laments the fact that he’s beginning to recognise more of his dad’s traits in him than he’s comfortable with. DeMarco Sr. has been conspicuous by his absence for most of Mac’s life and was seriously ill during the making of This Old Dog, inspiring the record’s emotionally conflicted closer, ‘Watching Him Fade Away’. He’s since recovered, but they’re no closer than they ever were.

“When I started writing these tracks, I didn’t know if I’d do anything with them; I wasn’t consciously working towards a record. I ended up with a handful of songs and I thought: ‘Cool, I’ll do some master recordings of these’, and then when I listened back, I thought no way could I show them to anybody. I was shocked by how personal they were; I was trying to understand where I stood in terms of my relationship with my dad. Some time passed, and I sat with the songs and got used to them, and I ended up sending them out into the world. It was definitely terrifying and weird. I don’t know if he’s heard them or not; I didn’t know if he ever would. There might be an interesting phone call coming.”

In some respects, this turn towards writing so personally marks a move away from his last release, Another One; the broken heart on that EP was presumably not DeMarco’s own, given that he’s been with his girlfriend, Kiera McNally, for eight years now. Instead, he was simply paying tribute to the evergreen love songs he grew up with. Given that he’s on one of the world’s hippest record labels, it’s always funny to hear him reel off the likes of James Taylor, Paul Simon, and Neil Young as influences; he’s a huge fan of the latter especially, claiming that his ultimate aim is to make his own Harvest and, perhaps less sincerely, asking fans to “kneel for Neil” when he treats them to his oft-aired cover of his fellow Canadian’s ‘Unknown Legend’.

“I spent the other day listening to The Beatles, all day long, just because I hadn’t done that for a while,” he says. “I think stuff like that will always hold the same importance to me. That kind of timeless music, those simple, fun love songs, those are what drove me to make my own music in the first place. I listen to a little bit of contemporary stuff, but I think I’m wary about trend-hopping. I could make some R&B-ish record with a load of DX7 piano on it, but everybody’s doing that right now, and I don’t want to play along.”

That’s not to say that there isn’t concrete evidence of musical progression on This Old Dog, which does bring in some piano work to stirring effect, most notably on ‘One More Love Song’. The woozy ‘On The Level’, which DeMarco has rather incongruously been opening recent live sets with, plays like an even bolder sequel to Salad Days’ experimental ‘Chamber Of Reflection’, whilst ‘Moonlight On The River’ is probably the most out-there thing he’s ever done, a seven-minute epic that drifts glacially towards a claustrophobic, feedback-drenched climax.

“On Salad Days, Another One, and even some of the songs off of 2, there was a little formula,” he explains. “I kind of accidentally crafted it, and you can hear it in terms of so many of the same chords being used, even if I recorded it a little differently every time. I could make those little ditties all day long, even if I’m not necessarily trying to punch in the same thing, so what I wanted to do was something a little off-centre from that approach. Acoustic guitars with no effects in the mix, not blowing anything out. Just little steps. I don’t think I was ever going to make a big, sexy pop record, and whenever I caught myself doing that, I found myself thinking: ‘What the fuck am I doing?’ It seemed so cheap and shitty. It doesn’t suit me.”

DeMarco was still living by the sea in Far Rockaway when he started work on This Old Dog, but was out in Los Angeles by the time he finished it. He mentions more than once during the course of the conversation that he’s never made more than one record in the same place, but that’s likely to change now that he’s put down roots on the west coast, where, for the first time, he has a little bit of security.

“I’ve just built a studio here, and I’m planning on sticking around. Hopefully, I’ll be able to do a couple more here, at least. I think the main thing about finally having a solid place to make music in is that I buy way too much gear, and most of it, I never use. That’s my main problem, or at least it was. I never had a dedicated music space like this before – it was just a corner of the room, as much of it as my girlfriend would permit me to take up. Now, I can close the door, shut the blinds and really let loose. I’ve just been in there for two days straight, working on new songs, because I can’t get out of tour mode – I can’t just sit on the couch watching TV.”

His road schedule remains a gruelling one, making a mockery of the slacker tag that’s so often ascribed to him; he’s back in the UK in November for a slew of dates that include an intimate three-night residency at London’s Coronet, which he’s dubbing ‘The Royal Macathon’. As the rooms get bigger and his audience broader, he’s able to enjoy a touch more luxury, and he’s even dialled down his trademark rambunctiousness, even if only by the most slender of increments.

“I’ve been looking after myself a little bit better on the road,” he says earnestly, before having an attack of conscience and correcting himself. “Well, actually, I was drinking way too much on this last tour. It’s just that I can’t do it like I used to anymore, and that’s because I did it for so long. My body doesn’t take it as well, so I’ve reeled it in a little, and it’s not like back in the day when we’d have no money, so we just slept on a couch or on the floor. I have a little bit more sway now. You know what, though? I watched Supersonic on the flight home, that Oasis documentary. That’s what 2017’s missing, my friend. Rock and roll! There’s absolutely none right now. Maybe we could use some more of it...”

This Old Dog is out now via Captured Tracks. Mac DeMarco plays nine UK shows from 17 November. For more information, please visit his official website.